JP5292020B2 - Liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display element achieving good display. <P>SOLUTION: The display includes: first and second transparent substrates; a liquid crystal layer exhibiting vertical alignment, which is sandwiched between the first and the second transparent substrates and has a retardation of from 360 nm to 1,000 nm; a first viewing angle compensating plate having negative biaxial optical anisotropy, disposed in the opposite side of the first transparent substrate to the liquid crystal layer, and having a retardation in thickness direction of from 90 nm to 350 nm and a retardation in an in-plane direction of from 5 nm to 50 nm; a second viewing angle compensating plate, which is an A-plate, disposed in the opposite side of the second transparent substrate to the liquid crystal layer, and having a retardation in the in-plane direction of from 10 nm to 100 nm; a first polarizing plate disposed in the opposite side of the first viewing angle compensating plate to the first transparent substrate; and a second polarizing plate disposed in the opposite side of the second compensation plate to the first transparent substrate and disposed in crossed Nicols arrangement with the first polarizing plate; wherein the retardation in the in-plane direction of the second viewing angle compensating plate is larger than the retardation in the in-plane direction of the first viewing angle compensating plate. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a liquid crystal display (LCD).

  As an in-vehicle information display device, there is a demand for a display device with a very low background luminance of a background display unit and a dark display unit intended for a high-grade appearance.

  Fluorescent display tube displays that have been widely used in the past have the disadvantages that the glass substrate used in the display is thick and heavy, and that the power source for driving is special.

  A liquid crystal display device is an example of a device that has a small display device weight and can use an in-vehicle power source as a driving power source. However, the conventional liquid crystal display device does not have sufficient contrast when viewed from the front and from the left and right.

  Note that in this specification, a liquid crystal display device refers to a display device including a liquid crystal display element that performs information display, a backlight that includes a light emitting light source, a drive circuit that performs operation control thereof, and a control circuit. .

  In recent years, a normally black liquid crystal display element has been developed that uses an inorganic LED as the light source of the backlight to substantially improve the contrast at that wavelength by making the light emission wavelength almost monochromatic. It is used as a device.

  A configuration in which a vertical alignment mode (VA mode) liquid crystal cell is arranged between polarizing plates arranged in a substantially crossed Nicols manner as a liquid crystal display element capable of good normally black display without depending on the emission wavelength of the backlight. It has been known. Here, the vertical alignment mode (VA mode) refers to a liquid crystal alignment mode in which liquid crystal molecules in a liquid crystal layer disposed between upper and lower glass substrates are aligned vertically or substantially perpendicular to the substrate. When the liquid crystal display element having the above configuration is observed from the normal direction of the glass substrate, the optical characteristics thereof are substantially the same as those of the two polarizing plates arranged in a crossed Nicol arrangement. That is, since the light transmittance is very low, a high-contrast display can be realized relatively easily.

  A viewing angle compensation plate (C plate) having negative uniaxial optical anisotropy or a viewing angle compensation plate (negative biaxial) having negative biaxial optical anisotropy on one or both of the upper and lower polarizing plates and the upper and lower glass substrates. An invention of a liquid crystal display element in which a film) is inserted is disclosed (for example, see Patent Document 1). According to this liquid crystal display element, even when observed from an oblique direction, an increase in light transmittance and a decrease in contrast are suppressed, and a good display can be realized.

  For this viewing angle compensation method, effective conditions regarding the in-plane retardation of the negative biaxial film and the in-plane slow axis arrangement have been proposed (for example, see Patent Document 2).

  Further, an invention of a liquid crystal display element that obtains good viewing angle characteristics by combining a substantially ½ wavelength plate having biaxial optical anisotropy and a C plate is disclosed (for example, Patent Document 3).

  As in the invention described in Patent Document 3, a liquid crystal display element that combines a negative biaxial film and a C plate instead of combining a substantially ½ wavelength plate having biaxial optical anisotropy and a C plate. The invention is also known (see, for example, Patent Document 4). Patent Document 4 describes that the in-plane retardation of the biaxial film is 190 nm or less, and the retardation in the liquid crystal layer of the applied liquid crystal cell is 200 nm to 500 nm.

  Multi-domain alignment in which liquid crystal molecules are aligned in a plurality of directions within one pixel is effective for obtaining good viewing angle characteristics even when a voltage is applied. In order to realize this in a VA mode liquid crystal display element, an oblique electric field alignment control method (for example, an electric field is generated in an oblique direction in a liquid crystal layer and liquid crystal molecules are aligned in that direction by devising an electrode shape (for example, Patent Document 5) and a method for controlling the alignment of liquid crystal molecules by bank-like protrusions formed on the substrate surface (for example, see Patent Document 6) are known.

  When emphasizing the viewing angle characteristics of the left and right orientation of the liquid crystal display element, it achieves good viewing angle characteristics by using a liquid crystal cell with a monodomain orientation, in which liquid crystal molecules are aligned in a uniform direction over the entire liquid crystal cell, rather than multi-domain orientation. can do. Uniform monodomain alignment is realized by, for example, a photo-alignment processing method for a vertical alignment film (for example, see Patent Document 7) or a rubbing processing method for a vertical alignment film having a specific surface free energy (for example, see Patent Document 8). Is possible.

  When the VA mode liquid crystal display element is operated at a duty of 1/4 to 1/240 by multiplex driving, the retardation Δnd of the liquid crystal layer needs to be at least 320 nm, preferably larger than 360 nm. This is because if the steepness in the electro-optical characteristics is not made as good as possible, it is difficult to maintain both high contrast characteristics, which is a feature of the VA mode, at high duty driving and maintaining high transmittance at the time of ON voltage application. .

  Currently, an optical film used for a liquid crystal display element is a raw film produced by a method of continuously forming a film from a raw material resin by a melt casting method or a melt extrusion method, and finally winding it into a roll. . In order to develop a phase difference in the in-plane direction and the thickness direction of the original film, stretching is mainly performed. The stretching step is a step of stretching the raw film in a heated state in a roll winding direction (MD direction) and a direction orthogonal to the MD direction (TD direction) by a roll-to-roll method.

  Many of the resin films that are distributed in the market as negative biaxial films are made of norbornene-based cyclic olefin (COP) as a material. The film is stretched to develop an in-plane slow axis in the MD direction or TD direction.

  In these films, when the in-plane retardation Re (the in-plane refractive index of the resin film is nx with respect to the slow axis direction, ny with respect to the fast axis direction, and d is the thickness of the film, Re = (nx−ny ) * D.) Is greater than 0 nm and less than or equal to 300 nm, preferably greater than 4 nm and less than or equal to 300 nm, more preferably greater than 30 nm and less than or equal to 300 nm, and the thickness direction retardation Rth (further the refractive index in the thickness direction). Is defined as Rth = ((nx + ny) / 2−nz) * d), which is equal to or less than 350 nm, and is an Nz factor used to express the refractive index ratio between the in-plane direction and the thickness direction. (Nz = (nx−nz) / (nx−ny)) is not a condition that is larger than 1 and smaller than 56, it is difficult to achieve in-plane uniformity of Re and Rth. It is thought that.

  Note that the thickness of the film after stretching is about several tens of μm. In addition, the material is improved based on the base film of polarizing plate that originally shows the optical characteristics of the C plate and triacetyl cellulose (TAC), which is used as a protective film, and the in-plane slow axis in the MD or TD direction. An optical film which is stretched so as to develop a negative biaxial film is also commercially available. The in-plane retardation Re of these films is narrower than that of norbornene-based COP, and is about 40 to 70 nm. The thickness direction retardation Rth is 120 nm or more and 220 nm or less.

  When a commercially available negative biaxial film is used and the invention described in Patent Document 2 is carried out, when the negative biaxial film is disposed only between the liquid crystal cell and the one-side polarizing plate, the retardation of the liquid crystal layer Δnd is less than about 500 nm. In addition, when a negative biaxial film is disposed between the liquid crystal cell and both side polarizing plates, the retardation Δnd of the liquid crystal layer is less than about 850 nm.

  However, as will be described later with reference to a comparative example, in a liquid crystal display element having a configuration in which a viewing angle compensation plate is disposed between a liquid crystal cell and both side polarizing plates, if the retardation Δnd of the liquid crystal layer is large, bright display There is a phenomenon in which the display becomes almost invisible at polar observation angles with deep left and right orientations, particularly at angles greater than 45 °. Therefore, in order to obtain a good display quality under a condition where the retardation Δnd is large, that is, a driving condition where the duty ratio is large, a method of arranging a biaxial film between the liquid crystal cell and the one-side polarizing plate, or Patent Document 4 A method of laminating and arranging a negative biaxial film and a C plate as described is considered effective.

  However, even in these methods, left-right asymmetrical light transmittance changes are observed when observing the horizontal direction during bright display, and in combination with a monodomain vertical alignment liquid crystal cell having a pretilt angle, left-right light transmission is performed when no voltage is applied. Asymmetry may be observed in the rate change.

Japanese Patent No. 2047880 Japanese Patent No. 3330574 Japanese Patent No. 3299190 Japanese Patent No. 3863446 Japanese Patent No. 3834304 Japanese Patent No. 2947350 Japanese Patent No. 2872628 JP 2005-234254 A

  An object of the present invention is to provide a liquid crystal display element capable of realizing good display.

  According to one aspect of the present invention, the first and second transparent substrates, the vertically aligned liquid crystal layer sandwiched between the first and second transparent substrates and having a retardation of 360 nm or more and 1000 nm or less, A first viewing angle compensation plate having negative biaxial optical anisotropy disposed on the opposite side of the first transparent substrate from the liquid crystal layer, and having a retardation of 90 nm or more and 350 nm or less in the thickness direction The first viewing angle compensation plate having a phase difference of 5 nm or more and 50 nm or less in the in-plane direction and the second viewing angle compensation which is an A plate disposed on the opposite side of the liquid crystal layer of the second transparent substrate. A first viewing angle compensation plate having a phase difference of not less than 10 nm and not more than 100 nm in the in-plane direction, and a first viewing angle compensation plate disposed on the opposite side of the first transparent substrate from the first viewing angle compensation plate. And the second transparent substrate of the second viewing angle compensation plate On the opposite side of the first polarizing plate and a second polarizing plate arranged in crossed Nicols, an in-plane slow axis of the first viewing angle compensation plate, and the first polarizing plate Are arranged so as to be orthogonal to the absorption axis of the second viewing angle, and are arranged so that the in-plane slow axis of the second viewing angle compensation plate and the absorption axis of the second polarizing plate are orthogonal to each other, the second viewing angle. A liquid crystal display element is provided in which the phase difference in the in-plane direction of the compensation plate is larger than the phase difference in the in-plane direction of the first viewing angle compensation plate.

According to another aspect of the present invention, the first and second transparent substrates and a vertically aligned liquid crystal layer sandwiched between the first and second transparent substrates and having a retardation of 360 nm or more and 1000 nm or less. And a first viewing angle compensation plate having negative biaxial optical anisotropy disposed on the opposite side of the first transparent substrate from the liquid crystal layer, and having a thickness direction of 90 nm or more and 350 nm or less A negative biaxial optical difference disposed on the opposite side of the liquid crystal layer of the first viewing angle compensation plate having a phase difference and a phase difference of 5 nm to 50 nm in the in-plane direction, and the second transparent substrate. A second viewing angle compensator having directionality, wherein the second viewing angle compensator has a phase difference of 90 nm to 150 nm in the thickness direction and a phase difference of 30 nm to 65 nm in the in-plane direction; 1 viewing angle compensation plate on the opposite side of the first transparent substrate A first polarizing plate placed on the opposite side of the second viewing angle compensation plate from the second transparent substrate, and a second polarizing plate arranged in crossed Nicols with the first polarizing plate. And an in-plane slow axis of the first viewing angle compensator and an absorption axis of the first polarizing plate are arranged to be orthogonal to each other, and the in-plane slow axis of the second viewing angle compensator The phase difference in the in-plane direction of the second viewing angle compensation plate is more than the phase difference in the in-plane direction of the first viewing angle compensation plate. also rather large retardation in the thickness direction of the second viewing angle compensating plate, the first liquid crystal display element have smaller than the phase difference in the thickness direction of the viewing angle compensation plate is provided.

  Further, according to another aspect of the present invention, the first and second transparent substrates and a vertically aligned liquid crystal layer sandwiched between the first and second transparent substrates and having a retardation of 300 nm or more and 1000 nm or less. And a first viewing angle compensation plate having negative biaxial optical anisotropy disposed on the opposite side of the first transparent substrate from the liquid crystal layer, and having a thickness direction of 90 nm or more and 350 nm or less A positive biaxial optical difference disposed on the opposite side of the liquid crystal layer of the first viewing angle compensation plate having a phase difference and a phase difference of 5 nm to 50 nm in the in-plane direction, and the second transparent substrate. A second viewing angle compensation plate having a directivity or a negative A plate, the second viewing angle compensation plate having a phase difference of 35 nm or more and 140 nm or less in an in-plane direction, and the first viewing angle compensation A first plate disposed on the opposite side of the plate from the first transparent substrate; An optical plate, and a second polarizing plate disposed in crossed Nicols on the opposite side of the second viewing angle compensation plate from the second transparent substrate, An in-plane slow axis of the viewing angle compensation plate and an absorption axis of the first polarizing plate are arranged to be orthogonal to each other, and the in-plane slow axis of the second viewing angle compensation plate and the second polarizing plate are arranged. A liquid crystal display device is provided in which the phase difference in the in-plane direction of the second viewing angle compensator is greater than the phase difference in the in-plane direction of the first viewing angle compensator. Is done.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display element which can implement | achieve favorable display can be provided.

  Prior to detailed description of liquid crystal display elements according to Examples and Comparative Examples, outlines of the liquid crystal display elements and the manufacturing method thereof will be described.

In the manufacture of liquid crystal display elements according to the following examples, modifications, and comparative examples, a glass substrate on which transparent electrodes (ITO electrodes) formed in a desired pattern on glass are arranged is Chisso Corporation. After forming a vertical alignment film using a petrochemical material, the substrate was subjected to alignment treatment by the rubbing treatment method described in Patent Document 8 described above. Note that an insulating film such as SiO ₂ may be formed between the glass substrate and the alignment film.

  Next, the two substrates subjected to the alignment treatment were bonded with a sealing material so that the vertical alignment films were close to each other and the rubbing directions were antiparallel.

  In bonding the substrates, a spherical spacer was used to control the distance between the two substrates to be 2 to 6 μm.

  A liquid crystal material having a refractive index anisotropy Δn of 0.08 or more and 0.26 or less and a negative dielectric anisotropy Δε is injected between the two glass substrates that are bonded to each other. Firing was performed at a temperature about 20 ° C. higher than the temperature for 1 hour. The pretilt angle of the liquid crystal molecules with respect to the substrate surface in the liquid crystal cell of the liquid crystal display element according to the manufactured example, modification, and comparative example was about 89.9 ° regardless of the values of Δn and Δε of the liquid crystal material.

  A polarizing plate was bonded to the outside of the two glass substrates of the liquid crystal cell so that the polarizing plate absorption axis was in a substantially crossed Nicols arrangement. SHC13U manufactured by Polatechno Co., Ltd. was used for the polarizing plate. A TAC base film having an in-plane retardation Re of about 3 to 5 nm exists on the bonding surface of the polarizing plate on the glass substrate side, and is bonded to the polarizing layer with an adhesive. In the simulation analysis, the in-plane retardation Re of the TAC base film was 3 nm, and the thickness direction retardation Rth was 50 nm.

  As the negative biaxial film, a norbornene-based COP film obtained by biaxial stretching was used.

  For the simulation analysis, “LCDMASTER 6.16” manufactured by Shintech Co., Ltd. was used.

  With reference to FIGS. 1 to 3, a visual angle characteristic simulation analysis at the time of bright display of a liquid crystal display element according to a comparative example will be described.

  FIG. 1 is a schematic view showing a liquid crystal display element according to a first comparative example.

  A monodomain vertical alignment type liquid crystal cell is disposed between the front side (upper side) polarizing plate 10 and the back side (lower side) polarizing plate 20 which are arranged in crossed Nicols. The monodomain vertical alignment type liquid crystal cell includes an upper glass substrate (transparent substrate) 4, a lower glass substrate (transparent substrate) 5, and a monodomain vertical alignment liquid crystal layer 30 sandwiched between the substrates 4 and 5. Is done. One negative biaxial film 3 is disposed between the lower glass substrate 5 of the liquid crystal cell and the rear polarizing plate 20.

  Each of the front and back polarizing plates 10 and 20 has a configuration in which the polarizing layer 1 is disposed on the TAC base film 2. Although not shown, a surface protective film made of TAC is disposed on the polarizing layer 1.

  In the illustrated azimuth coordinate system in which the horizontal orientation of the liquid crystal display element is defined as 180 ° -0 ° (9-3 o'clock) orientation, the rubbing orientation Rub of the upper glass substrate 4 is 270 ° and the rubbing of the lower glass substrate 5 is performed. The orientation Rub is 90 °, and the orientation orientation of molecules in the center of the liquid crystal layer 30 is 90 ° (12:00). Further, the absorption axis ab in the polarizing layer 1 of the front side polarizing plate 10 and the in-plane slow axis TACsl of the TAC base film 2 are arranged in the 135 ° azimuth direction, and those in the back side polarizing plate 20 are arranged in the 45 ° azimuth direction. Since the in-plane slow axis Bsl of the negative biaxial film 3 is disposed substantially orthogonal to the absorption axis of the adjacent polarizing plate, its orientation is 135 °. The in-plane retardation Re of the negative biaxial film 3 was 50 nm, and the thickness direction retardation Rth was 300 nm.

  When a simulation analysis was performed on the liquid crystal display element according to the first comparative example, the retardation Δnd of the liquid crystal layer 30 that provided the optimum viewing angle characteristics when no voltage was applied (background) was about 465 nm.

  FIG. 2 is a schematic view showing a liquid crystal display element according to a second comparative example. In the first comparative example, one negative biaxial film was disposed between the lower glass substrate 5 of the liquid crystal cell and the rear polarizing plate 20. In the second comparative example, the first negative biaxial film 3a is interposed between the lower glass substrate 5 and the rear polarizing plate 20, and the second is interposed between the upper glass substrate 4 and the front polarizing plate 10 of the liquid crystal cell. Negative biaxial film 3b is arranged. Other configurations are the same as those of the first comparative example.

  Since the in-plane slow axis Bsl1 of the first negative biaxial film 3a is substantially orthogonal to the absorption axis ab of the polarizing layer 1 of the polarizing plate 20 adjacent thereto, its orientation is 135 °. Further, since the in-plane slow axis Bsl2 of the second negative biaxial film 3b is substantially orthogonal to the absorption axis ab of the polarizing layer 1 of the adjacent polarizing plate 10, its orientation is 45 °.

  The in-plane retardation Re of the first and second negative biaxial films 3a and 3b was both 20 nm, and the thickness direction retardation Rth was both 300 nm.

  When a simulation analysis was performed on the liquid crystal display element according to the second comparative example, the retardation Δnd of the liquid crystal layer 30 that provided the optimum viewing angle characteristics when no voltage was applied (background) was about 825 nm.

  The inventor of the present application calculates the viewing angle characteristics at the time of left-right observation when the drive voltage is adjusted so that the light transmittance of the liquid crystal display element according to the first and second comparative examples is about 13 to 14% at the time of front observation. did.

  FIG. 3 is a graph showing the viewing angle characteristics during left-right observation in the liquid crystal display element according to the first comparative example (single-sided compensation) and the liquid crystal display element according to the second comparative example (double-sided compensation).

  The horizontal axis of the graph represents the horizontal observation angle in the unit “°”, and the vertical axis represents the light transmittance in the unit “%”. Curve a shows the viewing angle characteristic at the time of left-right observation of the liquid crystal display element (single-sided compensation) according to the first comparative example, and curve b shows the viewing angle characteristic at the time of left-right observation of the liquid crystal display element (double-sided compensation) according to the second comparative example. Show.

  From the curve b, it can be seen that in the liquid crystal display element (double-sided compensation) according to the second comparative example, the light transmittance is symmetric in the left-right direction, but the light transmittance is very low at a left-right observation angle of 45 ° or more. .

  Also in the liquid crystal display element according to the second comparative example actually manufactured, the display was hardly visible at the left and right observation angles of 45 ° or more. Further, in the actually manufactured liquid crystal display element, a color shift phenomenon in which the color tone of bright display changes significantly as the observation angle is deepened was observed remarkably.

  On the other hand, in the liquid crystal display element (single-sided compensation) according to the first comparative example that was actually manufactured, the display could not be recognized when observed from a deep angle. In addition, in the liquid crystal display element according to the first comparative example actually manufactured, almost no color shift was observed. However, as shown by the curve a, in the liquid crystal display element according to the first comparative example, the symmetry of the light transmittance change in the horizontal direction is poor.

  From the above, the inventors of the present application are effective in that the viewing angle compensation film is arranged only on one side of the liquid crystal cell in terms of improving viewing angle characteristics from a deep angle in the horizontal direction during bright display, It was considered that by arranging the viewing angle compensation film on both sides of the liquid crystal cell, the left-right symmetry of the viewing angle characteristic can be realized regardless of the pretilt angle of the liquid crystal layer.

  FIG. 4 is a schematic view showing the liquid crystal display element according to the first embodiment.

  Vertical alignment having a liquid crystal layer 30 substantially vertically aligned with respect to the upper glass substrate 4 and the lower glass substrate 5 between the front side (upper) polarizing plate 10 and the back side (lower) polarizing plate 20 arranged in crossed Nicols. A type liquid crystal cell is arranged. An optical film having negative biaxial optical anisotropy (negative biaxial film 3) is disposed between the lower glass substrate 5 of the liquid crystal cell and the back side polarizing plate 20, and the upper glass substrate 4 and the front side polarizing plate 10 are disposed. An optical film (A plate 6) having positive uniaxial optical anisotropy is disposed between them.

  Each of the front and back polarizing plates 10 and 20 has a configuration in which the polarizing layer 1 is disposed on the TAC base film 2. Although not shown, a surface protective film made of TAC is disposed on the polarizing layer 1.

  The rubbing orientation Rub of the upper glass substrate 4 is 270 °, the rubbing orientation Rub of the lower glass substrate 5 is 90 °, and the orientation orientation of molecules at the center of the liquid crystal layer 30 is 90 ° (12:00). Further, the absorption axis ab in the polarizing layer 1 of the front side polarizing plate 10 and the in-plane slow axis TACsl of the TAC base film 2 are arranged in the 135 ° azimuth direction, and those in the back side polarizing plate 20 are arranged in the 45 ° azimuth direction.

  The negative biaxial film 3 and the in-plane slow axes Bsl3 and Bsl6 of the A plate 6 are arranged substantially orthogonal to the absorption axis ab of the back-side polarizing plate 20 and the absorption axis ab of the front-side polarizing plate 10, respectively. Is preferred. Therefore, for example, the in-plane slow axis Bsl3 is arranged in the 135 ° azimuth and Bsl6 is arranged in the 45 ° azimuth.

  The inventor of the present application conducted a simulation analysis for obtaining optical parameters of the negative biaxial film 3 and the A plate 6 exhibiting good background viewing angle characteristics when no voltage is applied in the liquid crystal display element according to the first embodiment.

  First, the in-plane retardation Re3 of the negative biaxial film 3 and the in-plane position of the A plate 6 when the thickness direction retardation Rth of the negative biaxial film 3 is changed to 220 nm, 300 nm, and 350 nm. The optimal combination of the phase difference Re6 was determined. The optimum combination of Re3 and Re6 was Re3 and Re6 that give the retardation of the liquid crystal layer that minimizes the light transmittance observed from the right azimuth polar angle of 50 °.

  FIG. 5 shows an optimal combination of the in-plane retardation Re3 of the negative biaxial film 3 and the in-plane retardation Re6 of the A plate 6. In the figure, the horizontal axis represents the in-plane retardation Re3 of the negative biaxial film 3 in the unit “nm”, and the vertical axis represents the in-plane retardation Re6 of the A plate 6 in the unit “nm”.

  The point marked with a indicates the optimum combination of Re3 and Re6 when the retardation Rth in the thickness direction of the negative biaxial film 3 is 300 nm. Moreover, the point which attached | subjected the code | symbol b and c shows the optimal combination of Re3 and Re6 when the phase difference Rth of the thickness direction of the negative biaxial film 3 is 220 nm and 350 nm, respectively.

  From the figure, it is recognized that there is a linear relationship between Re3 and Re6 regardless of the retardation Rth in the thickness direction of the negative biaxial film 3.

  As a result of the analysis, under the optimum conditions, the light transmittance at the observation of the right azimuth polar angle of 50 ° was 0.02% or less. When the retardation Rth in the thickness direction of the negative biaxial film 3 is 220 nm, the retardation of the liquid crystal layer that minimizes the light transmittance is about 420 nm, and when the Rth is 350 nm, it is about 570 nm.

  Furthermore, the inventor of the present application obtained optimum values of Re3 and Re6 even when Rth takes other values, and confirmed that there is a linear relationship between them even when Rth = 90 nm, for example.

  From FIG. 5, in order to reduce the necessity of the A plate, that is, Re6> 0 nm, and to reduce the manufacturing difficulty of the A plate, that is, to increase Re6 as much as possible, the in-plane retardation Re3 of the negative biaxial film 3 is The range is preferably 5 nm ≦ Re3 ≦ 50 nm, and more preferably 10 nm ≦ Re3 ≦ 25 nm.

  In order to achieve a good background viewing angle characteristic under the negative biaxial film condition, the in-plane retardation Re6 of the A plate 6 is preferably in the range of 10 nm ≦ Re6 ≦ 100 nm, and 40 nm ≦ Re6. It is more desirable that the range is ≦ 60 nm.

  Furthermore, from the viewpoint that a negative biaxial film can be produced, a preferable range of the retardation Rth in the thickness direction of the negative biaxial film 3 is 90 nm ≦ Rth ≦ 350 nm, and a more preferable range is 220 nm ≦ Rth ≦ 350 nm.

  A preferable range of the retardation Δnd of the liquid crystal layer 30 is 360 nm ≦ Δnd ≦ 1000 nm, and more preferably 360 nm ≦ Δnd ≦ 540 nm.

  Next, the inventor of the present application fixes the retardation of the liquid crystal layer 30 to 525 nm, the thickness direction retardation Rth of the negative biaxial film 3 to 300 nm, and the optimum combination of Re3 and Re6 obtained by simulation analysis. The left-right viewing angle characteristics during bright display were calculated.

  FIG. 6 is a graph showing the Re3 dependence of the light transmittance when observed from the left-right azimuth polar angle of 50 °. Re6 is set to an optimum value as shown in FIG. 5 corresponding to the value of Re3.

  The horizontal axis of the graph represents the in-plane retardation Re3 of the negative biaxial film 3 in the unit “nm”, and the vertical axis represents the light transmittance when observed from the polar angle of 50 ° in the unit “%”. . The point on the straight line a indicates the light transmittance when observed from the left azimuth polar angle of 50 °, and the point on the straight line b indicates the light transmittance when observed from the right azimuth polar angle of 50 °.

  From the figure, it is understood that when the retardation of the liquid crystal layer 30 is 525 nm and the retardation of the negative biaxial film 3 in the thickness direction is 300 nm, the right and left light transmittances are equal when Re3 is about 22 nm. . In this case, Re6 is about 52 nm, and Re6> Re3.

  The inventor of the present application performed the same simulation analysis when Rth is another value. As a result, it was found that the symmetry was obtained when Re6> Re3.

  In addition, when the values of Re3 and Re6 were greatly different, a tendency was observed that the asymmetry of the viewing angle characteristic during left-right observation increases.

  In the liquid crystal display element according to the first embodiment shown in FIG. 4, the A plate is disposed between the glass substrate on one side and the polarizing plate. Since the retardation Rth in the thickness direction of the A plate is half of the in-plane retardation Re, the liquid crystal display device according to the first embodiment is disadvantageous when performing viewing angle compensation when the retardation Δnd of the liquid crystal layer is large. It is thought that it becomes.

  Therefore, the inventor of the present application introduces different optical parameters to the first negative biaxial film 3a and the second negative biaxial film 3b in the liquid crystal display element according to the second comparative example shown in FIG. The visual angle characteristics were analyzed by simulation.

  FIG. 7A is a schematic view showing a liquid crystal display device according to the second embodiment. The liquid crystal display element according to the second embodiment has the same configuration as the liquid crystal display element according to the second comparative example shown in FIG.

  FIG. 7B is a schematic view showing a liquid crystal display element according to a modification of the second embodiment (hereinafter referred to as a second modification). The liquid crystal display element according to the second modification has a configuration in which the TAC base film 2 of the front polarizing plate 10 is removed from the liquid crystal display element according to the second embodiment.

  The inventor of the present application, for the second embodiment, the thickness direction retardation Rth1 of the first negative biaxial film 3a, the thickness direction retardation Rth2 of the second negative biaxial film 3b, The analysis was performed to obtain the optimum values of the in-plane retardations Re1 and Re2 of the first and second negative biaxial films 3a and 3b, respectively fixed at 300 nm and 90 nm.

  In the second modification, Rth1 and Rth2 were fixed at 300 nm and 150 nm, respectively, and an analysis for obtaining the optimum values of Re1 and Re2 was performed.

  As the optimum values of Re1 and Re2, as in the case of the first example, the conditions under which the light transmittance was the lowest when observed from the right polar angle of 50 ° when no voltage was applied were determined.

  FIG. 8 shows an optimal combination of the in-plane retardation Re1 of the first negative biaxial film 3a and the in-plane retardation Re2 of the second negative biaxial film 3b.

  The horizontal axis of the figure represents the in-plane retardation Re1 of the first negative biaxial film 3a in the unit “nm”, and the vertical axis represents the in-plane retardation Re2 of the second negative biaxial film 3b. Expressed as “nm”.

  The point marked with a indicates the optimum combination of Re1 and Re2 in the liquid crystal display device according to the second embodiment. Moreover, the point which attached | subjected the code | symbol b shows the optimal combination of Re1 and Re2 in the liquid crystal display element by a 2nd modification.

  From the figure, it is recognized that Re1 and Re2 in the optimum combination are fairly close values in both the example and the modification, and that there is a linear relationship between Re1 and Re2.

  Note that when Re1 and Re2 were set to the optimum combination, the light transmittance observed from the right azimuth polar angle of 50 ° was 0.02% or less in any combination.

  In the case of the example, the retardation of the liquid crystal layer that minimizes the light transmittance was about 585 nm, and in the case of the modified example, it was about 600 nm.

  From the simulation showing the results in FIG. 8, for the second example and the second modification, the in-plane retardation Re1 of the first negative biaxial film 3a is preferably in the range of 5 nm ≦ Re1 ≦ 50 nm. It was found that the range of 10 nm ≦ Re1 ≦ 25 nm was more preferable. Further, it was found that the in-plane retardation Re2 of the second negative biaxial film 3b is preferably in the range of 30 nm ≦ Re2 ≦ 65 nm, and more preferably in the range of 40 nm ≦ Re2 ≦ 60 nm.

  Furthermore, it was found that the thickness direction retardation Rth1 of the first negative biaxial film 3a is preferably in the range of 90 nm ≦ Rth1 ≦ 350 nm, and more preferably in the range of 220 nm ≦ Rth1 ≦ 350 nm. Further, it was found that the range of 90 nm ≦ Rth2 ≦ 150 nm is effective as the retardation Rth2 in the thickness direction of the second negative biaxial film 3b.

  Further, it was found that the retardation Δnd of the liquid crystal layer 30 is preferably in the range of 360 nm ≦ Δnd ≦ 1000 nm, and more preferably in the range of 400 nm ≦ Δnd ≦ 600 nm.

  Next, the inventor of the present application analyzes the symmetry of the viewing angle characteristic during left-right orientation observation when the light transmittance when viewed from the front is set to about 14% for the liquid crystal display element according to the second modification. Went.

  FIG. 9 is a graph showing the Re1 dependency of the light transmittance when observed from the left-right azimuth polar angle of 50 °. Re2 is set to an optimum value as shown in FIG. 8 corresponding to the value of Re1.

  The horizontal axis of the graph represents the in-plane retardation Re1 of the first negative biaxial film 3a in the unit “nm”, and the vertical axis represents the light transmittance when observed from the polar angle of 50 ° in the unit “%”. ". The point on the straight line a indicates the light transmittance when observed from the left azimuth polar angle of 50 °, and the point on the straight line b indicates the light transmittance when observed from the right azimuth polar angle of 50 °.

  From the graph, it can be seen that when Re1 is about 22 nm, the right and left light transmittances are equal. At this time, Re2 is about 42 nm, and Re1 <Re2.

  The inventor of the present application performed the same simulation analysis for the second embodiment. As a result, it was found that good symmetry was obtained when Re1 <Re2.

  Comparing the graph of FIG. 6 (first embodiment) and the graph of FIG. 9 (second modified example), in FIG. 6, the light transmittance during bright display when observed from the right azimuth polar angle of 50 ° The light transmittance is about 5.8% when viewed from the left azimuth polar angle of 50 °, whereas it is about 3.5% in FIG. Smaller than the case. However, the display of both the first embodiment and the second modification can be visually confirmed. Since the light transmittance of the second comparative example is almost 0 as shown by the curve b in FIG. 3, the improvement in display quality at a deep observation angle is clear.

  As a result of research, the inventors of the present application have found that in the liquid crystal display elements according to the second embodiment and the modification, the thickness direction retardation Rth1 of the first negative biaxial film 3a and the second negative It has been found that setting the phase difference Rth2 in the thickness direction of the biaxial film 3b so that the difference between the two is as large as possible is desirable in order to achieve good display. In particular, high-quality display can be realized under the conditions of Rth1> Rth2 and Rth2 ≦ 150 nm.

  FIG. 10 is a schematic view showing a liquid crystal display device according to the third embodiment. The liquid crystal display device according to the third embodiment is not an optical film (A plate 6) having positive uniaxial optical anisotropy between the upper glass substrate 4 and the front polarizing plate 10, but positive biaxial optical anisotropy. Is different from the liquid crystal display device according to the first embodiment in that an optical film having an Nz factor (an optical film having a Nz factor in the range of 0 <Nz <1) is disposed. Instead of the positive biaxial film 7, an optical film having negative uniaxial optical anisotropy (an optical film with negative Nz = 0, a negative A plate) may be used.

  The positive biaxial film 7 includes (i) a method of controlling a refractive index in a three-dimensional orientation by stretching or shrinking a polycarbonate film in three axial directions, and (ii) a material having a negative photoelastic coefficient, such as polystyrene. Can be realized by a method of stretching in a uniaxial or biaxial direction in the plane, and positive biaxial films produced by these methods are on the market.

  A positive biaxial film is a biaxial film with Nz = 0.5, which is substantially equal to the in-plane retardation Re during frontal observation, regardless of the orientation when the thickness direction retardation is 0. There is. This film can be used as a phase difference plate for wide viewing angle circularly polarized light. In order to cancel the retardation of 50 nm in the thickness direction of the TAC base film of the polarizing plate, the retardation in the thickness direction is further reduced by − When a material having a negative photoelastic coefficient is used, it is considered more effective to use a negative A plate with Nz = 0 obtained by uniaxial stretching.

  In the following, the applicant conducted a simulation analysis on the assumption that the positive biaxial film and the negative A plate have the same wavelength dispersion characteristics as the norbornene-based COP.

  The inventor of the present application, regarding the third embodiment, Nz of the positive biaxial film 7 is 0.5, the retardation Rth in the thickness direction of the negative biaxial film 3 is 300 nm, and the negative biaxial film 3 An analysis was performed to find the optimum values of the in-plane retardation Re3 and the in-plane retardation Re7 of the positive biaxial film 7. Further, in the case where a negative A plate 7 (Nz = 0) was used instead of the positive biaxial film 7, an analysis for obtaining the optimum values of Re3 and Re7 was performed under the same conditions.

  As the optimum values of Re3 and Re7, as in the case of the first and second embodiments, the conditions under which the light transmittance when observed from the right polar angle of 50 ° is lowest when no voltage is applied are obtained. It was.

  FIG. 11 shows an optimal combination of the in-plane retardation Re3 of the negative biaxial film 3 and the in-plane retardation Re7 of the positive biaxial film 7 or the negative A plate 7.

  The horizontal axis of the figure represents the in-plane retardation Re3 of the negative biaxial film 3 in the unit “nm”, and the vertical axis represents the in-plane retardation Re7 of the positive biaxial film 7 or the negative A plate 7 in units. Expressed as “nm”.

  In the point which attached | subjected the code | symbol a, the optimal combination of Re3 and Re7 in the case of using the positive biaxial film 7 is shown. Moreover, the point which attached | subjected the code | symbol b shows the optimal combination of Re3 and Re7 when a negative A plate (Nz = 0) is used.

  From the figure, there is a linear relationship between Re3 and Re7 both when using a positive biaxial film (Nz = 0.5) and when using a negative A plate (Nz = 0). It is recognized that

  Further, referring to FIG. 5 showing the same analysis result for the A plate (Nz = 1), the absolute value of the rate of change (slope) decreases as the value of the Nz factor increases. Recognize.

  From the simulation showing the results in FIG. 11, in the third example, the in-plane retardation Re3 of the negative biaxial film 3 is preferably in the range of 5 nm ≦ Re3 ≦ 50 nm in the range of 0 ≦ Nz <1. It was found that the range of 10 nm ≦ Re3 ≦ 25 nm was more preferable. Further, it was found that the in-plane retardation Re7 of the positive biaxial film 7 or the negative A plate 7 is preferably in the range of 35 nm ≦ Re7 ≦ 140 nm, and more preferably in the range of 50 nm ≦ Re7 ≦ 140 nm.

  Furthermore, it was found that the thickness direction retardation Rth of the negative biaxial film 3 is preferably in the range of 90 nm ≦ Rth ≦ 350 nm, and more preferably in the range of 220 nm ≦ Rth ≦ 350 nm.

  Further, it was found that the retardation Δnd of the liquid crystal layer 30 is preferably in the range of 300 nm ≦ Δnd ≦ 1000 nm, and more preferably in the range of 360 nm ≦ Δnd ≦ 420 nm.

  Next, the inventor of the present application shows the light transmittance when the liquid crystal display element using the negative A plate (Nz = 0) instead of the positive biaxial film 7 is observed from the front in the third embodiment. An analysis was performed regarding the symmetry of the viewing angle characteristics when observing the left and right directions when the ratio was set to about 15%.

  FIG. 12 is a graph showing the Re3 dependence of the light transmittance when observed from the left-right azimuth polar angle of 50 °. Re7 is set to an optimum value as shown in FIG. 11 corresponding to the value of Re3.

  The horizontal axis of the graph represents the in-plane retardation Re3 of the negative biaxial film 3 in the unit “nm”, and the vertical axis represents the light transmittance when observed from the polar angle of 50 ° in the unit “%”. . The point on the straight line a indicates the light transmittance when observed from the left azimuth polar angle of 50 °, and the point on the straight line b indicates the light transmittance when observed from the right azimuth polar angle of 50 °.

  From the graph, it can be seen that when Re3 is about 22 nm, the right and left light transmittances are equal. Re7 at this time is about 85 nm as can be seen from FIG. In order to make the left-right viewing angle characteristics symmetric during bright display, it is considered necessary to satisfy Re3 <Re7.

  From the comparison of the graph of FIG. 6 (first example), the graph of FIG. 9 (second modified example), and the graph of FIG. 12 (third example), it is between the upper glass substrate 4 and the front side polarizing plate 10. It can be seen that as the value of the Nz factor of the optical film placed on the plate decreases, the light transmittance when observed from the left-right azimuth polar angle of 50 ° increases.

  In addition, between the upper side glass substrate 4 and the front side polarizing plate 10, in the case of FIG. 6 (1st Example), A plate (Nz = 1), in the case of FIG. 9 (2nd modification), two negative | negative. A shaft film (Nz> 1) and a negative A plate (Nz = 0) in the case of FIG. 12 (third embodiment) are arranged.

  The liquid crystal display element according to the third embodiment has a higher light transmittance at a deep observation angle in the horizontal direction during bright display than the liquid crystal display elements according to the first, second, and second modifications. It is a liquid crystal display element that can be held in the liquid crystal display.

  FIG. 13 is a schematic view showing a liquid crystal display device according to the fourth embodiment. In the liquid crystal display element according to the fourth embodiment, a C plate 8, which is an optical film having negative uniaxial optical anisotropy, is disposed between the first negative biaxial film 3 a and the lower glass substrate 5. This is different from the second modification shown in FIG. 7B.

  In the fourth embodiment, the in-plane retardation Re1 of the first negative biaxial film 3a is, for example, 15 nm, the thickness direction retardation Rth1 is 300 nm, and the in-plane position of the second negative biaxial film 3b. The phase difference Re2 is 50 nm, and the phase difference Rth2 in the thickness direction is 150 nm. Further, the thickness direction retardation of the C plate 8 is, for example, 300 nm.

  FIG. 14 is a graph showing the bright display left-right viewing angle characteristics of the liquid crystal display element according to the fourth embodiment in comparison with the second modification.

  This figure shows the left-right azimuth viewing angle characteristics simulated by setting the light transmittance during frontal observation to about 15%. In the simulation, the retardation of the liquid crystal layer of the fourth example was about 900 nm, and that of the second modification was about 600 nm.

  The horizontal axis of the graph represents the horizontal direction observation angle in the unit “°”, and the vertical axis represents the light transmittance in the unit “%”. A curve a indicates the left-right azimuth viewing angle characteristic regarding the fourth embodiment, and a curve b indicates that regarding the second modification.

  From the graph, it can be seen that both the fourth embodiment and the second modification can visually recognize the display at all angles. Further, it is recognized that the light transmittance of the fourth example is higher than that of the second modification at an angle exceeding 40 ° in both the left and right directions.

  By disposing the C plate 8 between the first negative biaxial film 3a and the lower glass substrate 5, it is possible to achieve good viewing angle characteristics even when the retardation of the liquid crystal layer is large. .

  The fourth embodiment is a liquid crystal display element having a configuration in which a C plate 8 is added between the first negative biaxial film 3a and the lower glass substrate 5 of the second modification. In any of the liquid crystal display elements of the first to third embodiments, the C plate 8 is disposed between the (first) negative biaxial films 3 and 3 a and the lower glass substrate 5, thereby The same effects as in the fourth embodiment can be obtained.

  In this case, in this case, the (first) negative biaxial films 3 and 3a, the C plate 8, and the optical film disposed between the upper glass substrate 4 and the front polarizing plate 10 (of the first embodiment). In the case of the second embodiment, the second negative biaxial film 3b, and in the case of the third embodiment, the positive biaxial film 7 or the negative A plate 7). The total retardation in the thickness direction of the film is preferably about 0.5 to 1 times the retardation of the liquid crystal layer. This is because even when the C plate 8 is used, when the retardation of the liquid crystal layer is too large, the viewing angle characteristic when no voltage is applied tends to deteriorate. The retardation of the liquid crystal layer in which good viewing angle characteristics are easily obtained is generally 1000 nm or less.

  In the fourth embodiment, one C plate is disposed between the first negative biaxial film 3a and the lower glass substrate 5, but a plurality of C plates may be disposed.

  FIG. 15 is a schematic view showing a liquid crystal display device according to the fifth embodiment. In the liquid crystal display device according to the fifth embodiment, the third negative biaxial film 3c is arranged between the first negative biaxial film 3a and the lower glass substrate 5 instead of the C plate 8. This is different from the fourth embodiment.

  In the fifth embodiment, the in-plane retardation Re1 of the first negative biaxial film 3a is, for example, 10 nm, the thickness direction retardation Rth1 is 300 nm, and the in-plane position of the second negative biaxial film 3b. The phase difference Re2 is 50 nm, and the phase difference Rth2 in the thickness direction is 150 nm. The optical characteristics of the third negative biaxial film 3c are the same as those of the first negative biaxial film 3a, the in-plane retardation Re1 is 10 nm, and the thickness direction retardation Rth1 is 300 nm. .

  FIG. 16 is a graph showing the bright display left-right viewing angle characteristics of the liquid crystal display element according to the fifth embodiment in comparison with the second modification.

  This figure shows the left-right azimuth viewing angle characteristics simulated by setting the light transmittance during frontal observation to about 15%. In the simulation, the retardation of the liquid crystal layer of the fifth example was about 945 nm, and that of the second modification was about 600 nm. Further, the in-plane retardation Re1 of the first negative biaxial film 3a in the second modified example is the in-plane retardation of the first and third negative biaxial films 3a and 3c in the fifth embodiment. It was equal to the sum of Re1 and Re3, and was set to 20 nm.

  The horizontal axis of the graph represents the horizontal direction observation angle in the unit “°”, and the vertical axis represents the light transmittance in the unit “%”. A curve a indicates the left-right azimuth viewing angle characteristic relating to the fifth embodiment, and a curve b indicates that relating to the second modification.

  From the graph, both the fifth example and the second modified example can visually recognize the display at all angles, and the fifth example shows that the second and second orientations are at angles exceeding 40 °. It can be seen that the light transmittance is higher than that of the modification.

  By arranging the third negative biaxial film 3c between the first negative biaxial film 3a and the lower glass substrate 5, even when the retardation of the liquid crystal layer is large, good viewing angle characteristics Can be realized.

  Note that the viewing angle characteristic of the fifth embodiment shown by the curve a in FIG. 16 is substantially equal to the viewing angle characteristic of the fourth embodiment shown by the curve a in FIG.

  In the fourth embodiment, as in the fifth embodiment, a plurality of C plates may be disposed between the first negative biaxial film 3a and the lower glass substrate 5. A plurality of negative biaxial films may be disposed between the first negative biaxial film 3 a and the lower glass substrate 5.

  The fifth embodiment is a liquid crystal display having a configuration in which a third negative biaxial film 3c is added between the first negative biaxial film 3a and the lower glass substrate 5 of the second modification. In the liquid crystal display elements of the first to third embodiments, the third negative electrode is interposed between the (first) negative biaxial films 3, 3 a and the lower glass substrate 5. By arranging the biaxial film 3c, it is possible to obtain the same effect as that of the fifth embodiment.

  In order to realize good viewing angle characteristics, the sum of the in-plane retardations of the first negative biaxial film 3a and the third negative biaxial film 3c is calculated only by the first negative biaxial film 3a. It is effective to set it below the optimum value when it is not arranged (the third negative biaxial film 3c is not arranged).

  For example, the in-plane retardation Re3 of the third negative biaxial film 3c is 1 nm ≦ Re3 <30 nm, the thickness direction retardation Rth3 is 90 nm ≦ Rth3 ≦ 350 nm, and the first negative biaxial film 3a It is effective that the sum of the in-plane retardation Re1 and the in-plane retardation Re3 of the third negative biaxial film 3c is 5 nm ≦ Re1 + Re3 ≦ 50 nm, more preferably 10 nm ≦ Re1 + Re3 ≦ 25 nm.

  As mentioned above, although this invention was demonstrated along the Example and the modification, this invention is not limited to these. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  It can be generally used for liquid crystal display elements. For example, it can be suitably used for a multiplex drive liquid crystal display device.

It is the schematic which shows the liquid crystal display element by a 1st comparative example. It is the schematic which shows the liquid crystal display element by a 2nd comparative example. It is a graph which shows the viewing angle characteristic at the time of right-and-left observation in the liquid crystal display element (single-sided compensation) by the 1st comparative example, and the liquid crystal display element (double-sided compensation) by the 2nd comparative example. It is the schematic which shows the liquid crystal display element by a 1st Example. FIG. 6 is a diagram illustrating an optimal combination of an in-plane retardation Re3 of the negative biaxial film 3 and an in-plane retardation Re6 of an A plate 6; It is a graph which shows Re3 dependence of the light transmittance when it observes from the left-right azimuth | direction polar angle of 50 degrees. (A) is the schematic which shows the liquid crystal display element by a 2nd Example, (B) is the schematic which shows the liquid crystal display element by the modification (henceforth 2nd modification) of a 2nd Example. FIG. It is a figure which shows the optimal combination of in-plane phase difference Re1 of the 1st negative biaxial film 3a, and in-plane phase difference Re2 of the 2nd negative biaxial film 3b. It is a graph which shows Re1 dependence of the light transmittance when it observes from the horizontal azimuth | direction polar angle of 50 degrees. It is the schematic which shows the liquid crystal display element by a 3rd Example. The optimum combination of the in-plane retardation Re3 of the negative biaxial film 3 and the in-plane retardation Re7 of the positive biaxial film 7 or the negative A plate 7 is shown. It is a graph which shows Re3 dependence of the light transmittance when it observes from the left-right azimuth | direction polar angle of 50 degrees. It is the schematic which shows the liquid crystal display element by a 4th Example. It is a graph which shows the bright display left-right viewing angle characteristic of the liquid crystal display element by a 4th Example compared with the 2nd modification. It is the schematic which shows the liquid crystal display element by a 5th Example. It is a graph which shows the bright display right-and-left viewing angle characteristic of the liquid crystal display element by a 5th Example compared with the 2nd modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polarizing layer 2 TAC base film 3 Biaxial film 3a 1st biaxial film 3b 2nd biaxial film 3c 3rd biaxial film 4 Upper glass substrate 5 Lower glass substrate 6 A plate 7 Positive biaxial film 8 C plate 10 Front side polarizing plate 20 Back side polarizing plate 30 Monodomain vertically aligned liquid crystal layer ab Polarizing layer absorption axis TACsl TAC film in-plane slow axis Bsl Biaxial film slow axis Bsl1 First biaxial film slow axis Bsl2 First 2 biaxial film slow axis Bsl3 Negative biaxial film 3 slow axis Bsl6 A plate 6 slow axis Rub rubbing orientation on glass substrate

Claims (18)

First and second transparent substrates;
A vertically aligned liquid crystal layer sandwiched between the first and second transparent substrates and having a retardation of 360 nm or more and 1000 nm or less;
A first viewing angle compensation plate having negative biaxial optical anisotropy disposed on a side opposite to the liquid crystal layer of the first transparent substrate, wherein the retardation is 90 nm or more and 350 nm or less in the thickness direction. And a first viewing angle compensator having a phase difference of 5 nm to 50 nm in the in-plane direction,
A second viewing angle compensation plate, which is an A plate, disposed on the opposite side of the second transparent substrate from the liquid crystal layer, and has a second viewing angle having a phase difference of 10 nm to 100 nm in the in-plane direction. A compensation plate;
A first polarizing plate disposed on the opposite side of the first viewing angle compensation plate from the first transparent substrate;
On the opposite side of the second viewing angle compensation plate from the second transparent substrate, the first polarizing plate and a second polarizing plate arranged in crossed Nicols,
The in-plane slow axis of the first viewing angle compensation plate and the absorption axis of the first polarizing plate are arranged to be orthogonal to each other,
The in-plane slow axis of the second viewing angle compensation plate and the absorption axis of the second polarizing plate are arranged to be orthogonal to each other,
A liquid crystal display element in which a phase difference in an in-plane direction of the second viewing angle compensation plate is larger than a phase difference in an in-plane direction of the first viewing angle compensation plate. A phase difference in an in-plane direction of the first viewing angle compensator is 10 nm or more and 25 nm or less;
The liquid crystal display element according to claim 1, wherein a phase difference in an in-plane direction of the second viewing angle compensation plate is 40 nm or more and 60 nm or less. The retardation of the liquid crystal layer is 360 nm or more and 540 nm or less,
The liquid crystal display element according to claim 1, wherein the first viewing angle compensation plate has a phase difference of 220 nm or more and 350 nm or less in a thickness direction.   The liquid crystal display element according to claim 1, further comprising a C plate disposed between the first transparent substrate and the first viewing angle compensation plate. And a third viewing angle compensation plate having negative biaxial optical anisotropy disposed between the first transparent substrate and the first viewing angle compensation plate, wherein the thickness is 90 nm or more in the thickness direction. A third viewing angle compensator having a phase difference of 350 nm or less and a phase difference of 1 nm or more and less than 30 nm in the in-plane direction;
The sum of the phase difference in the in-plane direction of the first viewing angle compensation plate and the phase difference in the in-plane direction of the third viewing angle compensation plate is 5 nm or more and 50 nm or less. A liquid crystal display element according to 1.   6. The liquid crystal display element according to claim 5, wherein a sum of a phase difference in an in-plane direction of the first viewing angle compensation plate and a phase difference in an in-plane direction of the third viewing angle compensation plate is 10 nm or more and 25 nm or less. First and second transparent substrates;
A vertically aligned liquid crystal layer sandwiched between the first and second transparent substrates and having a retardation of 360 nm or more and 1000 nm or less;
A first viewing angle compensation plate having negative biaxial optical anisotropy disposed on a side opposite to the liquid crystal layer of the first transparent substrate, wherein the retardation is 90 nm or more and 350 nm or less in the thickness direction. And a first viewing angle compensator having a phase difference of 5 nm to 50 nm in the in-plane direction,
A second viewing angle compensation plate having negative biaxial optical anisotropy disposed on the opposite side of the second transparent substrate from the liquid crystal layer, wherein the retardation is 90 nm or more and 150 nm or less in the thickness direction. A second viewing angle compensator having a phase difference of 30 nm to 65 nm in the in-plane direction;
A first polarizing plate disposed on the opposite side of the first viewing angle compensation plate from the first transparent substrate;
On the opposite side of the second viewing angle compensation plate from the second transparent substrate, the first polarizing plate and a second polarizing plate arranged in crossed Nicols,
The in-plane slow axis of the first viewing angle compensation plate and the absorption axis of the first polarizing plate are arranged to be orthogonal to each other,
The in-plane slow axis of the second viewing angle compensation plate and the absorption axis of the second polarizing plate are arranged to be orthogonal to each other,
The phase difference in the plane direction of the second viewing angle compensating plate, the first much larger than the phase difference in the in-plane direction of the viewing angle compensation plate, retardation in the thickness direction of the second viewing angle compensator the first liquid crystal display element have smaller than the phase difference in the thickness direction of the viewing angle compensation plate. A phase difference in an in-plane direction of the first viewing angle compensator is 10 nm or more and 25 nm or less;
The liquid crystal display element according to claim 7, wherein a phase difference in an in-plane direction of the second viewing angle compensation plate is 40 nm or more and 60 nm or less. The retardation of the liquid crystal layer is 400 nm or more and 600 nm or less,
The liquid crystal display element according to claim 7, wherein the first viewing angle compensation plate has a phase difference of 220 nm or more and 350 nm or less in the thickness direction.   10. The liquid crystal display element according to claim 7, further comprising a C plate disposed between the first transparent substrate and the first viewing angle compensation plate. 11. And a third viewing angle compensation plate having negative biaxial optical anisotropy disposed between the first transparent substrate and the first viewing angle compensation plate, wherein the thickness is 90 nm or more in the thickness direction. A third viewing angle compensator having a phase difference of 350 nm or less and a phase difference of 1 nm or more and less than 30 nm in the in-plane direction;
The sum of the phase difference in the in-plane direction of the first viewing angle compensation plate and the phase difference in the in-plane direction of the third viewing angle compensation plate is 5 nm or more and 50 nm or less. A liquid crystal display element according to 1.   The liquid crystal display element according to claim 11, wherein a sum of a phase difference in an in-plane direction of the first viewing angle compensation plate and a phase difference in an in-plane direction of the third viewing angle compensation plate is 10 nm or more and 25 nm or less. First and second transparent substrates;
A vertically aligned liquid crystal layer sandwiched between the first and second transparent substrates and having a retardation of 300 nm or more and 1000 nm or less;
A first viewing angle compensation plate having negative biaxial optical anisotropy disposed on a side opposite to the liquid crystal layer of the first transparent substrate, wherein the retardation is 90 nm or more and 350 nm or less in the thickness direction. And a first viewing angle compensator having a phase difference of 5 nm to 50 nm in the in-plane direction,
A second viewing angle compensator arranged on the opposite side of the second transparent substrate from the liquid crystal layer and having a positive biaxial optical anisotropy or a negative A plate, A second viewing angle compensator having a phase difference of not less than 35 nm and not more than 140 nm in the direction;
A first polarizing plate disposed on the opposite side of the first viewing angle compensation plate from the first transparent substrate;
On the opposite side of the second viewing angle compensation plate from the second transparent substrate, the first polarizing plate and a second polarizing plate arranged in crossed Nicols,
The in-plane slow axis of the first viewing angle compensation plate and the absorption axis of the first polarizing plate are arranged to be orthogonal to each other,
The in-plane slow axis of the second viewing angle compensation plate and the absorption axis of the second polarizing plate are arranged to be orthogonal to each other,
A liquid crystal display element in which a phase difference in an in-plane direction of the second viewing angle compensation plate is larger than a phase difference in an in-plane direction of the first viewing angle compensation plate. A phase difference in an in-plane direction of the first viewing angle compensator is 10 nm or more and 25 nm or less;
The liquid crystal display element according to claim 13, wherein a phase difference in an in-plane direction of the second viewing angle compensation plate is 50 nm or more and 140 nm or less. The retardation of the liquid crystal layer is 360 nm or more and 420 nm or less,
The liquid crystal display element according to claim 13 or 14, wherein the first viewing angle compensation plate has a phase difference of 220 nm or more and 350 nm or less in the thickness direction.   The liquid crystal display element according to claim 13, further comprising a C plate disposed between the first transparent substrate and the first viewing angle compensation plate. And a third viewing angle compensation plate having negative biaxial optical anisotropy disposed between the first transparent substrate and the first viewing angle compensation plate, wherein the thickness is 90 nm or more in the thickness direction. A third viewing angle compensator having a phase difference of 350 nm or less and a phase difference of 1 nm or more and less than 30 nm in the in-plane direction;
The sum of the phase difference in the in-plane direction of the first viewing angle compensation plate and the phase difference in the in-plane direction of the third viewing angle compensation plate is 5 nm or more and 50 nm or less. A liquid crystal display element according to 1.   18. The liquid crystal display element according to claim 17, wherein a sum of a phase difference in an in-plane direction of the first viewing angle compensation plate and a phase difference in an in-plane direction of the third viewing angle compensation plate is 10 nm or more and 25 nm or less.

Images